In many oilfield applications, logging equipment is used to gain a better understanding of a specific subterranean formation. For example, a logging tool may be deployed downhole into a wellbore via a wireline and operated to determine characteristics of the surrounding formation. However, logging equipment often is rated for a certain temperature limit above which the equipment is susceptible to damage. As a result, difficulties may arise in utilizing logging equipment in a variety of high temperature well applications, such as enhanced oil recovery operations involving steam injections.
Throughout the world, an increasing number of enhanced oil recovery projects are being employed to recover hydrocarbon fluids, such as oil. A substantial percentage of the enhanced oil recovery projects and enhanced oil recovery oil production results from the application of thermal recovery methods. Thermal recovery primarily utilizes steam injection techniques to recover heavy oil, and such techniques are growing in popularity and importance as an approach to meeting global oil demand.
During enhanced oil recovery operations, monitoring of formation properties in substantial detail at different spatial locations can be important. The monitoring is achieved through placement of permanent sensors and/or logging tools to obtain the desired measurements. However, the high temperatures prevailing in many of these operations can limit the feasibility of using logging tools in obtaining the desired information.
For example, thermal-assist gas-oil gravity-drainage (TAGOGD) techniques are employed for recovering heavy oil in heavily fractured carbonate formations, but such techniques employ substantial heat. In some applications, TAGOGD techniques substantially improve oil recovery rates, but the heavy oil must be heated to reduce its viscosity and to allow it to drip/drain downwardly via gravity. Oil extracted from the carbonate formation accumulates in a fractured oil rim, from which it may be produced through wells intersecting the fractured region. In this type of application, it is important to monitor and manage the oil rim position and thickness, however, the injection of steam to heat the formation restricts the use of conventional reservoir monitoring/logging tools.